With the increasing array density of successive generations of non-volatile memory chips, it is desirable to incorporate and merge other functions, and thus other devices, onto the non-volatile memory chips. Many times, however, the non-volatile memory chips incorporating other functions and technologies are not cost competitive as compared to the alternative of combining separate chips at the card or package level, each being produced with independently optimized technologies. Any significant addition of process steps to an existing non-volatile memory technology in order to provide added functions, such as high speed logic, SRAM, or DRAM, rapidly becomes cost prohibitive due to the added process complexity and decreased yield.
Incorporating 1T-RAM capability into a non-volatile memory chip is one of the desired features. The 1T-RAM offers combinations of high density, low power consumption, high speed, and low cost easily compatible with logic and other embedded memory processes. One advantage of the 1T-RAM cell compared to an SRAM cell is its significantly smaller size (about one-third to about one-fourth the size of an SRAM cell), and one advantage of the 1T-RAM cell compared to a DRAM cell is its simplicity of integration in standard logic processes.
Thus, there is a need for non-volatile memory chips having other circuitry, such as 1T-RAM cells, incorporated on a non-volatile memory chip.